High and Low viscosity ATF.

[DWC28]

There have been many OEMs which recently have changed from a heavier viscosity ATF to a lower viscosity. Several reasons have been given, but one is for fuel economy.
DEXRON-III was a high viscosity fluid and DEXRON-VI is a low viscosity fluid.
MERCON-V was a high viscosity and MERCON-LV is a low viscosity fluid.
TOYOTA T-IV is a high viscosity and TOYOTA-WS is a low viscosity.
HONDA Z-1 is a high viscosity and HONDA DW-1 is a low viscosity.
NISSAN MATIC J is a high viscosity and NISSAN MATIC S is a low viscosity.
HYUNDAI SP-III is a high viscosity and HYUNDAI SP-IV is a low viscosity.
It is possible to make all of these fluids using the same chemistry (same friction) but different base oils.

 

[BISCUT]

MaxLife seems to meet most of the listed fluid spec's with whatever base oil they are using.

 

[eljefino]

Originally Posted By: DWC28

It is possible to make all of these fluids using the same chemistry (same friction) but different base oils.


Pretty sure the friction characteristics are what make fluids incompatible.

Also Dex III has poor viscosity retention so after a while of useage Dex VI will be thicker.

 

[bepperb]

In the Toyota literature for the rollout of WS they specifically stated that WS and T-IV were of a different viscosity when new but WS was more resistant to shear and they were similar in viscosity during most of their service life (which Toyota still thinks is lifetime).

I'm not sure if this is the same case for the other fluids but a look through some UOA's would probably be easy enough to do.

 

[NHGUY]

And ATF+4 is what?

 

[440Magnum]

Originally Posted By: NHGUY
And ATF+4 is what?


More like Dexron III in initial viscosity, and also holds it better.

I hear that Dex VI actually is better in vis retention and low oxidation than ATF+4. And I know one person who's been running it in a Chrysler 41TE transaxle as a "test" because of that- so far so good, but I wouldn't recommend it! ATF+4 is a good semi-syn fluid... LIGHT YEARS better than ATF+3 and the original DexIII its based on, even if in some ways Dex VI beats it.

 

[Whitewolf]

Originally Posted By: 440Magnum
Originally Posted By: NHGUY
And ATF+4 is what?


More like Dexron III in initial viscosity, and also holds it better.

I hear that Dex VI actually is better in vis retention and low oxidation than ATF+4. And I know one person who's been running it in a Chrysler 41TE transaxle as a "test" because of that- so far so good, but I wouldn't recommend it! ATF+4 is a good semi-syn fluid... LIGHT YEARS better than ATF+3 and the original DexIII its based on, even if in some ways Dex VI beats it.


ATF+4 wouldn't even come close to DEXRON-VI in most areas of performance. There is an SAE paper outlining the differences between these various fluids. It doesn't need to be looked into, it's already been done and published.

 

[440Magnum]

Originally Posted By: Whitewolf

ATF+4 wouldn't even come close to DEXRON-VI in most areas of performance. There is an SAE paper outlining the differences between these various fluids. It doesn't need to be looked into, it's already been done and published.


His experiment was not to see if Dex was better (that IS known). Its to see if a Chrysler transmission can tolerate the different friction modifier package IN ORDER TO USE the better long-life fluid. The older ones like the 41TE have been notorious for really needing the specific friction modifier package of ATF+3 or +4. +3 was just a sucky fluid. Oxidized at a horrendous rate, sheared, you name it. At least +4 doesn't do that.

My current dilemma is whether or not I should dump the ATF+4 in my SRT's Tremec manual trans. GM fills the same tranny with Dexron VI, and there are countless aftermarket fluids that are better than ATF+4 for the application and actually produce better shifting by doing a better job of eliminating the "Tremec nibble" into second gear... but Chrysler only warranties ATF+4.

 

[Ken2]

Originally Posted By: BISCUT
MaxLife seems to meet most of the listed fluid spec's with whatever base oil they are using.
Ah....doesn't meet the specs, but comes close enough that it works well.

 

[MolaKule]

Originally Posted By: DWC28
There have been many OEMs which recently have changed from a heavier viscosity ATF to a lower viscosity. Several reasons have been given, but one is for fuel economy.
DEXRON-III was a high viscosity fluid and DEXRON-VI is a low viscosity fluid.
MERCON-V was a high viscosity and MERCON-LV is a low viscosity fluid.
TOYOTA T-IV is a high viscosity and TOYOTA-WS is a low viscosity.
HONDA Z-1 is a high viscosity and HONDA DW-1 is a low viscosity.
NISSAN MATIC J is a high viscosity and NISSAN MATIC S is a low viscosity.
HYUNDAI SP-III is a high viscosity and HYUNDAI SP-IV is a low viscosity.
It is possible to make all of these fluids using the same chemistry (same friction) but different base oils.


What is the point of this comment and what do you consider a "High" viscosity ATF and what do you consider a "Low" viscosity ATF>

The viscosity difference at 100C is about 1 cSt kinematic viscostity. What about the Brookfield viscosities?

 

[jake88]

Originally Posted By: BISCUT
MaxLife seems to meet most of the listed fluid spec's with whatever base oil they are using.


It is impossible to meet both the high and low temperature specs because the viscosity of all those specs does not actually overlap. There is a case to be made that a high quality synthetic fluid will perform as a replacement for all those fluids, a case that Valvoline makes (and that my company makes). It is a technical judgement from the oil company, not a blessing by the OEM. The frictional properties are not all that different, the OEMs simply chose to use a lighter fluid to reduce churning losses and improve CAFEs.

We have customers using our multi-vehicle (7.5cSt@100C) in the Dex VI and Merc LV applications with no issues whatsoever (unless 0.1mpg loss bothers you).

 

[Whitewolf]

You need to study more.
If you need help then our services are available.

 

[DWC28]

When looking for a replacement fluid; low viscosity fluids will generally replace other low viscosity fluids and high will replace high. Two fluids are close to making a universal coverage; MERCON V type and DEXRON VI type. Friction properties have moved close together (no more Type F) and newer fluids have longer lifetimes (100,000 miles v. 20,000 miles).

 

[meep]

Originally Posted By: 440Magnum
Originally Posted By: NHGUY
And ATF+4 is what?


More like Dexron III in initial viscosity, and also holds it better.

I hear that Dex VI actually is better in vis retention and low oxidation than ATF+4. And I know one person who's been running it in a Chrysler 41TE transaxle as a "test" because of that- so far so good, but I wouldn't recommend it! ATF+4 is a good semi-syn fluid... LIGHT YEARS better than ATF+3 and the original DexIII its based on, even if in some ways Dex VI beats it.



Dex VI has more grip than the atf+3/4, which are friction modified (though I dislike that term, now, as many fluids are "F/M"). That's why the programming in the 41TE and it's predecessor didn't like it. the extra friction caused the computers to continually chatter the clutches during shifts because they were locking in too quickly. For this reason, in an AT, I wouldn't consider them easily compatible. That said, I've known several people to cross between the two in the RWD jeeps (42RE, 44RE?) with no ill effects. I suspect that those units had less computer bias in their shifts, using more old-school valve body activity to modulate pressures, instead of pulse-width solenoids. This makes them more resilient. Just my theory based on fooling with them for a while.

In your MT--- the only concern I'd have is synchro behavior. As long as the fluids don't do anything bad to the synchro material, it'd probably be ok to try. Personally, I'd probably go a 3rd route and either use a quality ATF+4 like castrol, or just go to amsoil. I trust both of them, and would see them as better suited than dex VI.

 

[Whitewolf]

Originally Posted By: DWC28
There have been many OEMs which recently have changed from a heavier viscosity ATF to a lower viscosity. Several reasons have been given, but one is for fuel economy.
DEXRON-III was a high viscosity fluid and DEXRON-VI is a low viscosity fluid.
MERCON-V was a high viscosity and MERCON-LV is a low viscosity fluid.
TOYOTA T-IV is a high viscosity and TOYOTA-WS is a low viscosity.
HONDA Z-1 is a high viscosity and HONDA DW-1 is a low viscosity.
NISSAN MATIC J is a high viscosity and NISSAN MATIC S is a low viscosity.
HYUNDAI SP-III is a high viscosity and HYUNDAI SP-IV is a low viscosity.
It is possible to make all of these fluids using the same chemistry (same friction) but different base oils.

It's not possible to make all of these with one chemistry because for one thing they are using different friction materials and the friction characteristic is a function of fluid, friction material, reaction surface and control system. There is an SAE paper that you should read. I'll try to find the number for you.

 

[Whitewolf]

Originally Posted By: Whitewolf
Originally Posted By: 440Magnum
Originally Posted By: NHGUY
And ATF+4 is what?


More like Dexron III in initial viscosity, and also holds it better.

I hear that Dex VI actually is better in vis retention and low oxidation than ATF+4. And I know one person who's been running it in a Chrysler 41TE transaxle as a "test" because of that- so far so good, but I wouldn't recommend it! ATF+4 is a good semi-syn fluid... LIGHT YEARS better than ATF+3 and the original DexIII its based on, even if in some ways Dex VI beats it.


ATF+4 wouldn't even come close to DEXRON-VI in most areas of performance. There is an SAE paper outlining the differences between these various fluids. It doesn't need to be looked into, it's already been done and published.

SAE 2007-10-3987

 

[Whitewolf]

That should have been 2007-01-3987, sorry.

 

[rslifkin]

Originally Posted By: meep
That said, I've known several people to cross between the two in the RWD jeeps (42RE, 44RE?) with no ill effects. I suspect that those units had less computer bias in their shifts, using more old-school valve body activity to modulate pressures, instead of pulse-width solenoids. This makes them more resilient. Just my theory based on fooling with them for a while.


That theory is 100% correct. The 42/44/46RE trannies are hydraulic control with an electronic governor to determine shift points. OD and TC lockup are solenoids, but they're not PWM, just on or off. The computer has no control over how it shifts, just when it shifts. As a result, it'll shift harder with grabbier fluid, but it won't care other than that.